Westerholm, Maria
- Department of Molecular Sciences, Swedish University of Agricultural Sciences
Abstract
Anaerobic digestion has been a widely used technology in animal manure treatment, but cost-effective anaerobic processes for pathogen inactivation remain challenging, and more importantly, the underlying mechanisms are still poorly understood. This study therefore investigated biothermal-hydrolysis at 55 C-degrees combined with a 37 C-degrees mesophilic process to enhance anaerobic treatment for hygienization and compared its effectiveness to a singlestep mesophilic process. Pathogens inactivation kinetics, factors and morphologies were analyzed and a modified time-temperature relationship was established to provide a framework for high-solids anaerobic digestion. Results from the stable period during over 500 days of operation showed that the combined anaerobic system inactivated culturable Escherichia coli, Salmonella spp., and Enterococcus spp. to below detection. In contrast, the single mesophilic process failed to achieve comparable outcomes. The kinetics and morphologies results indicated that high temperature was the most significant impact factor and most of the pathogens were inactivated in the biothermal-hydrolysis reactor due to cell membrane disruption. Compared to mesophilic conditions, biothermal hydrolysis conditions increased the inactivation rates of Salmonella and E. coli by >3-fold and 10-fold. Enterococcus showed minimal morphological changes in cells with the slowest thermal inactivation rate (k(d) = 3.71-3.89 d(-1)). Factor analysis showed that volatile fatty acids and ammonia have limited effects on pathogens' inactivation under mesophilic conditions. Methane production was increased by 7 % - 15 % in this combined system, highlighting its effectiveness in high-solids anaerobic digestion. Overall, the biothermal hydrolysis combined with mesophilic methane fermentation benefited the treatment of animal manure by enhancing hygienization and bioenergy production.
Keywords
High solids manure; Pathogen inactivation; Anaerobic digestion; Temperature; Exposure time; Volatile fatty acid
Published in
Chemical Engineering Journal
2025, volume: 518, article number: 164651
Publisher: ELSEVIER SCIENCE SA
SLU Authors
UKÄ Subject classification
Other Chemical Engineering
Publication identifier
- DOI: https://doi.org/10.1016/j.cej.2025.164651
Permanent link to this page (URI)
https://res.slu.se/id/publ/142940